This invention relates to a cage for confining animals, particularly to a cage for experimental animals of smaller size such as mice and rats. More specifically, the invention deals with a hermetically sealed, ventilated cage suitable for confining and rearing relatively small experimental animals in a germ free, hygienically favorable environment. The cage in accordance with the invention may be used in such a manner that a multiplicity (e.g. tens or even hundreds) of such cages are arranged in columns and rows.
The laboratory animal cage has been known and used extensively which comprises a molded plastic casing or enclosure in the form of an open top box, with a wirework lid closing the open top of the casing for confining an experimental animal or animals. For feeding the confined animal, a water dispenser has been employed which has an elongated spout inserted in the casing through an opening formed in a side or end wall of the casing. U.S. Pat. No. 4,346,672 to Niki discloses an example of such water dispenser.
It has also been proposed to hermetically close the open top casing of the cage with a solid outer lid, which overlies a wirework inner lid, and to ventilate the interior of the casing with germ free air. The caged animals may be infected with germs. The air exhausted from within the cage may contain such germs. Should such air be allowed to fill the laboratory, the experimenters may be infected with the germs or may develop an allergy. It is therefore important that the cage be sealed hermetically and be ventilated so as not to contaminate the laboratory air.
Thus the ventilation system requires not only a conduit for supplying germ free air into the cage but also another conduit for exhausting the possibly contaminated air from within the cage. As these conduits are inserted in the cage through openings formed therein, the gaps between the conduits and the edges of the openings must be sealed against the escape of the contaminated cage air.
In a known ventilation system for the cage, an air supply conduit inserted into the cage is formed with a number of holes through which fresh air is supplied into the cage. In this type of ventilation system, fresh air supplied through the holes impinges directly upon small animals within the cage or causes relatively strong forced flows of air within the cage. This is not desirable for small animals raised in the cage for a long time.